[Synthetic biocompatible degradable material for juvenile bone cyst treatment]

Owing to advances in operative techniques and biotechnology, bone replacement biocompatible materials have recently come into focus for orthopaedic and trauma surgeons. Bone lytic lesions, such as tumorous bone defects, diseases simulating cancer, chronic inflammatory lesions or skeletal injuries, often require stabilisation of the skeleton and treatment of the bone affected. Juvenile bone cysts are benign lytic lesions posing a threat to bone compactness in childhood. They are benign, fluid containing bone cavities, lined with a membrane consisting of thin vascularised connective tissue with scattered osteoclast-like cells. These cysts are usually diagnosed between; five and twenty years of age outside this age range their occurrence is rare.

The group comprised the patients treated for juvenile bone cysts at the Department of Paediatric Surgery, Orthopaedics and Traumatology between 2001 and 2007. In the 2001-2003 period, 24 patients were treated with Depo-Medrol. Between January 2005 and December 2007, 31 patients with the same diagnosis were treated by minimally invasive application of chronOs Inject.

The aim of the study was to compare these two methods of juvenile cyst therapy, i.e., the most widely used method of repetitive Depo-Medrol applications against the novel method based on filling the cyst with chronOs Inject, a synthetic biocompatible resorbable material. An alternative hypothesis assumed that the new method would result in fewer necessary operations in patients with juvenile cyst and better treatment outcomes, as evaluated by Neer's criteria for bone cyst therapy.

A total of 20 surgical interventions were performed in 18 patients treated by chronOs Inject and 100% cyst healing without necessity of additional surgery was achieved. Of the 24 patients treated with Depo-Medrol, 12 patients (50%) showed cyst healing wit no further surgery required. A total of 69 applications were needed.

An impetus to introduce the novel method of juvenile cyst treatment stemmed from the unsatisfactory results of the previous treatment with repetitive Depo-Medrol applications requiring additional open surgery and spongioplasty to fill the cyst. For filling cysts and other benign bone defects jeopardizing bone stability, such as deep metaphyseal fibrous defect, non-ossifying fibroma, enchondroma or fibrous dysplastic lesion, synthetic tricalcium phosphate in the form of chronOs granules was used, but without the possibility of minimally invasive percutaneous application. As soon s the resorbable chronOs Inject became available, the minimally invasive method of filling cysts with this material was adopted.

The results showed that, in the patients treated by the chronOs Inject method, the outcomes achieved were significantly better than those in the patients treated with Depo-Medrol. The difference was in the number of operations needed, which were significantly fewer in the chronOs Inject method, as well as in the overall treatment outcome, with significantly more frequent excellent results in the chronOs Inject method.